1. Field of the Invention
The present invention relates to a tyre for motor vehicles, i.e. a tyre having a high transversal curvature so as to offer an adequate contact surface with the road surface when the motor vehicle is leaning to turn a bend.
2. Description of the Related Art
Preferably, the tyre of the present invention is intended to be used in a rear wheel of motor vehicles of the “Sport Touring” type, i.e. sports motor vehicles intended to offer high performance in terms of power, comfort and mileage on motorways and streets, in cities and/or outside cities and/or off-road, with a wet or dry road surface.
“Sport Touring” motor vehicles typically have a large piston displacement (equal to or greater than 800 cm3) and/or high power (equal to or greater than 110 HP). However, on the market there are already motor vehicles having a piston displacement equal to 1400 cm3 and power equal to 155 HP.
It is known that the tyres for rear wheels of such motor vehicles must ensure a high versatility of use both when driving in a straight line and cornering, always ensuring high traction and grip on the road surface in order to allow an optimal transfer of power and an adequate braking action, also with a load of two people and on any type of road surface (wet, dry, regular and/or irregular asphalt, etc.) and/or route (city streets, motorways, mountain roads with a large number of bends, etc.).
Such tyres must also ensure comfort, driving stability, controllability, directionality, road-holding, high mileage and regular wear.
It is known how the behaviour of the tyre during travel is greatly influenced by the number, orientation, distribution and shape of the grooves formed on the tread band, and thus by the particular pattern of such a tread band.
The aforementioned grooves for example promote the grip of the tyre on the road surface and the draining of water in the case of a wet road surface. However, such grooves weaken the structure of the tread band, making it more subject to wear. They can also generate noise and vibrations.
EP 0 906 836 describes a tyre for a motor vehicle the tread band of which comprises a central region astride of an equatorial plane of the tyre, two shoulder regions arranged on axially opposite sides with respect to the central region and two intermediate regions each arranged between the central region and a respective shoulder region. A plurality of grooves are formed in the tread band that extend from opposite sides with respect to the equatorial plane up to the axially outermost portion of the shoulder region and according to a direction that in the central region is substantially circumferential, in the shoulder regions is substantially transversal and in the intermediate regions changes progressively from substantially circumferential to substantially transversal going from the equatorial plane outwards. The grooves formed on one side of the tyre with respect to the equatorial plane thereof are staggered along the circumferential direction with respect to the corresponding grooves formed on the other side of the tyre.
EP 1 884 377 describes a tyre for motor vehicle the tread band of which comprises two groups of curvilinear grooves inclined with respect to the equatorial plane of the tyre, such groups alternating in the circumferential direction and being arranged on both sides of the tyre with respect to the equatorial plane thereof, so as to mirror and be staggered from each other in the circumferential direction. Each group of grooves comprises two or more grooves that are substantially parallel to one another and inclined by an angle of between 5° and 85° with respect to the circumferential direction. All of the grooves extend up to the shoulder regions of the tread band.